


Now you see me. Now you don't.

by Elijah_Dentwood



Category: Supernatural
Genre: Invisibility, M/M, Sibling Incest, Voyeurism, Wall Sex
Language: English
Status: Completed
Published: 2013-09-08
Updated: 2013-09-08
Packaged: 2017-12-26 00:42:51
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 578
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/959542
Author URL: https://archiveofourown.org/users/Elijah_Dentwood/pseuds/Elijah_Dentwood
Summary: <blockquote class="userstuff">
              <p>Cas is just checking in, but he sees more than he bargained for. He can't help but watch.</p>
            </blockquote>





	Now you see me. Now you don't.

He doesn't notice much at first. Dean and Sam have always been this way. They talk to one another in a fashion that appears to be impolite, but he has come to realize that it is a way that humans show affection to one another, particularly male humans. 

It isn't until Sam is fucking Dean – even in his own mind he whispers the word _fucking_ , because he's certain it's blasphemy – that he identifies that their relationship doesn't fit the human norm. 

Siblings are not supposed to love each other this way, and Castiel is sure that Dean and Sam know this. He wonders if he should remind them. He has been trying to remind Dean of the reward of virtue and though he hasn't come far this does seem to be a slide in the opposite direction. 

He only arrived invisibly so that he could check on them. Dean never readily admits to being wounded or troubled. It takes a closer observation, one at which Cas is far more adept at than spotting intimate gestures, to understand when Dean needs him. 

It takes a moment to remember that he cannot be seen. His vessel instinctively steps back, knowing that this is a moment he should not see. He has arrived just as Sam is pushing his swollen cock – another hushed word – into Dean. His stomach tightens and he thinks that it must be disgusting, horror at this violation. He begins to reach out for Sam, to pull him away from Dean. 

Sam's movements cause Dean to make a noise that Cas has never heard him make. It reminds him of pain, but somehow of worship. He stops and stares at Dean's face, his cheeks flushed, lips red and wet. His legs are wrapped around Sam tightly. 

Sam is tainted. He has been trying to edge Dean towards the knowledge that he will have to be destroyed. He knows it is hard to contemplate the destruction of a brother, but the fate of the world rests on this point. 

'Oh God,' Dean breathes. 

Cas' fists tighten at his side. He hates every moment of it, but his eyes are fixed on the way that Sam's cock moves into Dean. It's wrong and it's wrong that he is watching it. 

He should leave. He should come back when Dean's mind is clear of this, when he can think straight. Cas knows that humans are lust driven, that they cannot help it. He knows this of Dean, the man whose soul he carried from Hell. Still, it is a sin. 

Dean groans when Sam slams him hard into the wall. Their movements are practiced but frantic. Cas finds himself pushing his palm against his vessel's hardening cock and tilts his head. He's aroused by this – the demon tainted Sam pounding into his Dean, the human he holds so dear. 

'Gonna fill you up,' Sam says between thrusts, 'fuck...Dean, _Dean_ ' 

Dean's mouth opens and his head tips back as he covers Sam's chest in splatters of pearly-white come. Cas palms his own cock hard through his trousers. Sam grunts out a few last thrusts into Dean and then slumps against him. 

Sam seems to loose strength. He pulls Dean up and away from him, letting a thick drop of come leak from Dean's still stretched hole. 

With a shudder Cas is palming through his pants at his cock, riding out his own orgasm. 

He already knows he'll be back for more.


End file.
